BENSTED — ON THE GEOLOOT OE M;\.IDSTONE. 



337 



a portion of a small stem, eight inches long, which is converted into 

 black flint, to the extent of six or seven inches, while the remainder 

 is a friable carbonate of lime ; the general aspect of this specimen, 

 and the indications of eight irregular branches, prove at once its 

 exog(!nous character. The cone found associated with this wood is 

 in every respect such a fruit as a tree of the kind above described 

 would produce. It bears a close resemblance to a fossil from the 

 Greensand of Dorsetshire, discovered by Dr. Buckland, and figured 

 in the 'Possil Plora of Great Britain' under tlie name of Ahics oh- 

 lonc/ala. In its general form, and in the shape of the scales and seeds, 

 the Maidstone specimen is decidedly distinct. Unfortunately, the 

 outer surface is so much worn that the external figure of the scales 

 cannot be accurately defined, but the sections show their propor- 

 tionate thickness ; and as Abies is distinguished from Finns by the 

 thinness of the ends of the scales, the affinity of the fossil is clearly 

 pointed out. There is an opening at the base of the cone occasioned 

 by the removal of the stalk (PI. xix. fig. 1), and an accidental oblique 

 fracture exhibits the internal structure. In the longitudinal section 

 thus exposed (fig. 2), the scales are seen to be rounded and broad 

 at their base, and to rise gradually anJ become thin at their outer 

 terminations (fig. 3). The seeds are oblong, and one seed is embedded 

 within the base of each scale ; in some instances there appears to be 

 the remains of the embryo." There are about twenty-three seeds 

 observable in the sections. 



This limestone group is followed by a series of chert beds or sili- 

 ceous hassock. The chert is nearly black, and in places very shat- 

 tery ; the more solid ])arts are very hard. An interesting occurrence 

 took place a few years since, which elucidates in one way how flint 

 veins in the chalk may be shattered in situ, as they are seen to be in 

 some localities in the Isle of Wight. The stone is thrown down in 

 my quarry in immense quantities, and in the fall of a large mass 

 of some hundreds of tons the concussion so acted upon the brittle 

 texture of the chert-seams as to shiver them into thin fragments, 

 while the limestone witli which they were intercalated in the block 

 was scarcely at all aih cted. 



The next group of strata, which, from the occurrence in it of the 

 bones of that reptile, I have called the Iguanodon group, consists of 

 two thin layers of very light-coloured limestone with intercalated 

 seams of hassock, much of the loose and " shaky" portions of which 

 consist of stems and nodules similar to the Sponr/ites Benstcdii. 



Hitherto very few shells have been met with, but in this group we 

 find tlie first distribution of a very characteristic one, Trigonia alee- 

 forniis. A Trigonia, but of another species, T. sjmiosa, occurs in the 

 upper bed of irregular ferruginous stone ; the specimens of which are 

 usually converted into chalcedony having the lines upon the shells 

 clearly defined, but in these Iguanodon beds casts only are met with, 

 a residue of white powder being all that remains of the shells ; it is 

 thus very rarely tliat the fossils can be extracted from the stone, 

 little more than the impressions in most cases remaining. 



